1. Field of the Invention
This invention relates to a linescan apparatus for detecting pattern on a surface of a product.
2. Description of the Prior Art
A linescan apparatus for detecting salient pattern on a surface of a product is known which detects salient pattern on a surface of a product, particularly, a circuit board to detect for defects, such as misinserted leads or missing or mis-sized components, by directing beams of light towards the surface along a first angular direction. The intensity of the light reflected along a second direction from each of a plurality of successive thin strips running across the surface is sensed by a linescan camera which moves relative to the circuit board. The output signal produced by the linescan camera, as the linescan camera moves across the circuit board, are processed to obtain image data representative of each of the strips. Only the image data representative of predetermined regions within each strip where defects may occur are retained. The retained image data are then analyzed to determine if defects are present.
Such linescan apparatus is disclosed in U.S. Pat. No. 4,811,410.
However, there is a drawback that it is impossible to detect salient pattern of a surface of the product, or of components mounted on a circuit board to be detected. In other wards, there is a drawback that it is impossible to detect that a component soldered on a circuit board does not surly seat on the circuit board; only one pin of an IC circuit mounted on a circuit board by soldering is not soldered, for the pin does not reach to the surface of the circuit board; or a component soldered leans.